One of the first people thought to have been killed by gunfire in the Americas has been found in a burial plot near Lima in Peru, scientists have said.

A skull bearing a gunshot hole was discovered amongst the remains of 72 bodies in a suburb of the capital.

Archaeologists believe the bodies were those of ancient Incas killed by Spanish conquistadors 500 years ago.

Forensics experts using a powerful scanning microscope later found fragments of metal on the skull.

"There may have been Incas and other native people killed by Europeans before him, but this is our oldest example so far," Peruvian archaeologist Guillermo Cock, who led the excavations in Lima, is quoted as saying by the Washington Post newspaper.

"We didn't expect it. We saw this skull and saw the almost round hole and thought people must have been shooting around here recently," Mr Cock, whose research is funded by National Geographic, said.

One of the forensics experts who analysed the skull said his team had tried to rule out all other possible causes of the hole, such as a rock from a slingshot, a spear or a sledgehammer.

"We all thought it was a million-to-one chance that we would find any traces of metal on a skull that old, but it was worth a try," said Al Harper, director of the Henry C Lee Institute of Forensic Science in West Haven, Connecticut, in the US.

Indigenous support

The skull is thought to have belonged to an Inca man who was involved in the 1536 siege of Lima.

The bodies seemed to have been buried hastily in shallow graves instead of being wrapped and put in the ground in the traditional Inca way.

"Some of the bodies also showed signs of terrible violence," Mr Cock said.

"They had been hacked, torn, impaled - injuries that looked as if they had been caused by iron weapons - and several had injuries on their heads and faces that looked as if they were caused by gunshots."

Mr Cock said the nature of the injuries found on the bodies - made with indigenous weapons such as stone axes and arrows - indicated that the conquistadors would have had some kind of native support to help in their conquest.

"That really confirms... native support for the conquerors was very important.

"The chronicles do not acknowledge the participation of the natives... [they] tell you that a couple of dozen cavalry men defeated the Inca troops in Lima."